The Optical Morphology Core will play an essential role in supporting the overall goals of the Center. The Specific Aims of this core are three-fold. First, to provide reliable, accessible, and state-of-the-art microscopic technology to all Center members that will facilitate their study of Gl cellular signaling cascades. Second, to educate and train Center members in the use of both basic and sophisticated cellular imaging methods. Emphasis will be placed on providing technical instruction as well as educating faculty about how such approaches can expand the scope and breadth of their scientific programs. Third, development and application of state-of-the-art optical imaging technologies to Gl tissues/cells including; high resolution, real-time computer/video imaging of live cells; confocal microscopy coupled with computer-based 3-D image reconstruction; Fluorescence Resonance Energy Transfer (FRET) applications to measure dynamic protein-protein interactions; Fluorescence Recovery After Photobleaching (FRAP) that allows the quantitation of protein recruitment/turnover; expression and use of fluorescence-based bioprobes that facilitates the study and localization of specific signaling molecules including both proteins and lipids; and the development and application of specific photoactivatable caged-compounds that allow a precise temporal and spatial activation of desired signaling molecules in live cells.